Joint for rock drills



Feb. 21, 1956 B. E. R. LOFQVIST JOINT FOR ROCK DRILLS Filed Sept. 5, 1951 E: r J =5 7 United States Patent JOINT FOR ROCK DRILLS- Bengt Erik Ragnwald Liifqvist, Sandviken, Sweden, assignor to Sandvikens Jemvcrks Aktiebol'ag, Sandviken, Sweden, a joint stock company Application September 5, 1951, Serial No. 245,111 Claims priority, application Sweden'Ocfoher 18, 1950 4 Claims. (Cl. 2'87114)- In my copending patent application No. 182,583 description is given of a device for attaching a drill crown to a drill rod or two drill rods to each other or the like, in which the drill rod and/or drill crown is furnished in the vicinity of the place of attachment with shallow depressions separated by a ridge or the like.

The diflerent parts are attached to each other by means of a sleeve provided with one or more holes through which the attaching devices are put down: in such a manner that they extend over the ridges down inthe depressions.

Owing to the attaching devices projecting into the holes of the sleeve at the ridge attachment between the parts is obtained.

In the said patent application is further described a modification of the above device characterized mainly by only one depression arranged at each rod and the attaching device being taken down through only one hole of the encircling sleeve so that it extends over the ridge formed by the outside portions of the two rod ends.

The present invention relates to improvements and further developments in drills device whereby the same is simplified and at the same time further strengthened. Unlike the conical and screwthreaded connections the device has good detachment facilities. Owing to the possibility of moving the joint parts a little in relation to each other in the course of drilling the fatigue stresses are decreased while at the same time the length of life of the parts is appreciably increased.

For a more complete understanding of the nature and advantages of this invention reference is to be had to the following detailed description, which describes the best illustrative embodiment of this invention known to me, taken in connection with the accompanying drawing in which:

Fig. 1 shows a side view, partially in section, of a drill according to the invention and Fig. 2 a portion of the sleeve surrounding the rod ends,

Fig. 3 shows a section through the joint of the drill in Fig. 1 taken along line 33, and

Fig. 4 a locking or fixing device shown tions.

Referring now to the drawing, numerals 10 and 11 denote respectively two rod two drill portions to be connected. Numeral 12 indicates a drill collar fixed on one of the rod portions and 13 indicates a rock-drill crown having a hard metal cutting insert 14. The rod ends portions to be connected are surrounded by a sleeve of steel or the like 15 provided with openings 16 and 17. Between the openings 16 and 17 there is sunken portion or recess 18 for accommodating a middle portion of a locking or fixing device 19 which last stretches extends beyond the recess 18 into the openings 16, 17 down into depressions 20, 21 in the rod portions 10, 11, by which, with a certain amount of play, displacement in relation to each other both of the rod portions 10, 11 and of the slee-e i5 is prevented. Thus, when the drill is drawn out of the bore hole, the locking or fixing device 19 will in two projecof the above-stated joint 2,735,704 Patented. Feb.- 21, 1956 be grippedfirmly between the side faces of the depres sions 20, 21 and the edges 29, 30 of the sleeve: holes, thereby loeldng the parts to each other by a wedging; or jamming action.

The lockingv or fixing device 19 preferably should com. prise a central part of spring material, for example; of a leaf. spring, suit-ably provided with a thicker wearing; part 22 at each end where the stress: is greatest. Accord ing to one embodiment there is employed as wearing part a flattened tube of appropriate material.

The clearing hole through the drill rod is designated by numeral 23; To prevent leakage of the flushingat the joint a packing ring 24 of suitable materialt for example rubber, or the like, is. arranged to restagainst the extreme parts of the rodends, whichparts 25 should, preferably, be turned, the packing ring being fitted a. groove 26 of. the surrounding sleeve 15. In. this way there isobtained very good packing. Withr heavy stresses inthe drilling work, to prevent the fixing device 19 being damaged andthe sleeve 15 displaced, the rod portion.

11 extending in the drilling direction should be provided with a forged collar 12,, or a collar fixedby mechanical; Particularly suitable is. a. rubber collar comprised of an, inner rubber sleeve 28F, or the like,.,and an outer metal case 27 which presses the rubber sleeve against the drill rod. The rubber sleeve might be vulcanised on the drill rod.

An advantage of the construction according to the invention is the ease with which the connection of the rod parts 10 and 11 is performed. The extension rod is provided with a sleeve and locking or fixing device, and the open end of the said sleeve is fitted over the drill rod portion 10 projecting from the drill-hole. One end of the resilient locking or fixing device will first be caused by the said drill end to move up towards the edge 29 of the opening 16 and then to snap down in the hollow 20 thus attaching rod ends and sleeve together.

As many changes could be made in the above construction and many apparently widely diiferent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matters contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a percussion rock drill rod and the like, separable drill rod members having non-circular sections, each of said members being provided with a recess in a side wall near but spaced from its respective end, a sleeve fitting over the ends and having an inner surface corresponding in shape to said non-circular drill rod members, said sleeve being provided with two longitudinally spaced openings in the wall thereof, said openings being normally located partly coincident with said recesses with said rod members abutting within the sleeve, a single elongated locking device extending along the part of said sleeve between said openings and having its ends projecting inwardly through said openings into said recesses, the distance between the remote ends of said openings being less than the longitudinal extent of said locking device, said locking device comprising a flat spring having relatively thick ends, the spaces provided by said recesses being inclined outwardly at their near ends to form spaces suflicient to freely accommodate the ends of said locking device to allow slight relative movement between the rod members and sleeve to reduce fatigue stresses in operation, the distance between the inner surface of said sleeve adjacent the openings and the extremities of the inclined portions of said recesses being less than the thickness of the ends of said locking device whereby upon further relative movement the drill rod members and sleeve are secured together by wedging action.

2. A percussion rock drill rod according to claim 1, and in which said sleeve is provided with a recess extending longitudinally between said openings for receiving the intermediate portion of said locking device.

3. A percussion rock drill rod as defined in claim 1, in which the openings in the sleeve are situated along a line substantially parallel with the drill axis.

4. In a percussion rock drill rod and the like, separable drill rod members having non-circular sections, each of said members being provided with a recess in a side wall near but spaced from its respective end, a sleeve fitting over the ends and having an inner surface corresponding in shape to said non-circular drill rod members, said sleeve being provided with two longitudinally spaced openings in the wall thereof, said openings being normally located partly coincident with said recesses with said rod members abutting within the sleeve, a single elongated locking device extending along the part of said sleeve between said openings and having its ends projecting inwardly through said openings into said recesses, the distance between the remote ends of said openings being less than the longitudinal extent of said locking device, said locking device comprising a flat spring having relatively thick ends, the spaces provided by said recesses being of sufiicient size to accommodate the ends of said locking device freely to allow slight relative movement between the rod members and sleeve to reduce fatigue stresses in operation, the distance between the remote inside edges of said openings of said sleeve and the respective near extremities of said recesses being less than the thickness of the corresponding end of said locking device when said sleeve and rods are in a relative position where said edge is coincident with said extremity, whereby relative movement between the drill rod members and sleeve in either axial direction is limited by said ends of said locking device being jammed between said remote edges and near extremities.

References Cited in the file of this patent UNITED STATES PATENTS 465,202 Preston Dec. 15, 1891 516,602 Kershaw Mar. 13, 1894 650,412 McLellan May 29, 1900 882,171 Schoenner Mar. 17, 1908 1,086,312 Blaha Feb. 3, 1914 1,136,987 Wakfer Apr. 27, 1915 1,282,928 Peirce Oct. 29, 1918 1,887,640 Hickman Nov. 15, 1932 2,259,797 Cohen Oct. 21, 1941 2,322,803 Koch June 29, 1943 2,473,388 Rambo June 14, 1949 FOREIGN PATENTS 275,514 Great Britain Aug. 11, 1927 

